To compare the effects of 1 year of treatment with alendronate 70 mg once weekly and 35 mg twice weekly with treatment with 10 mg daily in postmenopausal women with osteoporosis as measured by changes in BMD at the lumbar spine. To assess the safety and tolerability of 1 year of treatment with alendronate 70 mg once weekly and 35 mg twice weekly compared to treatment with 10 mg daily in postmenopausal women with osteoporosis. To compare the effects of 1 year of treatment with alendronate 70 mg once weekly and 35 mg twice weekly with treatment with 10 mg daily in postmenopausal women with osteoporosis as measured by changes in BMD at the hip (total hip, femoral neck, and trochanter) and total body. To assess the effect of 1 year of treatment with alendronate 10 mg daily on the rate of bone turnover as assessed by biochemical markers (NTx and BSAP) in postmenopausal women with osteoporosis. To assess the effect of 2 years of treatment with alendronate 70 mg once weekly and alendronate 35 mg twice weekly comapared to treatment with alendronate 10 mg daily on BMD at the lumbar spine, hip (total hip,femoral neck, and trochanter), and total body; the rate of bone turnover as assessed by biochemical markers (NTx and BSAP); and the safety and tolerability in postmenopausal women with osteoporosis